Semiconductor packages typically include a so-called package substrate on which a semiconductor die is adapted. Many such package substrates as well as other substrates are formed of a core material. Historically, this core material has been made with a halogenated flame retardant material.
More recently, halogen free (HF) core materials had been introduced, which typically include aluminum trihydrate Al(OH)3 as a flame retardant. Aluminum trihydrate functions by releasing water to quench flames and thus acts as a flame retardant. However, aluminum trihydrate begins to decompose at solder reflow temperatures used in processing the substrates. As such, if its water of hydration is released, this release can cause delamination and blistering on the HF substrate at reflow temperatures. Such delamination/blistering can lead to unacceptable yields, as well as device failures.